When the spectacle wearers go to the places for some activities or leisures where the sun shines so harsh that they are exposed to strong ultra-violet rays contained therein, or when they work for a long time in front of a display of office automation equipment, they try to prevent hazardous rays from penetrating into their eyes, for examples, by overhanging another pair of light-transmission control spectacles on the spectacles in use which is intended for correction of vision or by suspending a frame with light-transmission control lenses mounted therein with clips on the frontal part of the spectacles frame in use.
However, such overhanging of two spectacle frames bothers the wearers because it increases the weight of the spectacles as a whole. When said frame is suspended on the spectacles in use, its weight tends to be lopsided to the frontal part thereof, so that the spectacles becomes vulnerable to being displaced from its normal position on the face.
In view of such inconveniences as mentioned above, recently, a pair of spectacles for correction of vision has been proposed, on the rims of whose frame certain number of hooks are provided, on which hooks light transmission control lenses are sustained. However, it was not popular among the users because those hooks look unshapely and turn to be dangerous objects when said auxiliary lenses are removed therefrom.
By the way, a pair of rimless spectacles, on the respective lenses of which holes are bored, into which rod members protruding from a bridge and bracket endpieces are inserted so as to hold the lenses in place, has been popular among the recent wearers who favor eyeglasses wide in view, light in weight and with a sophisticated design rather than a pair of spectacles whose lenses are held by the rims surrounding them.
With the above rimless spectacles, said clip-type lens frame can not be directly suspended on its lenses. All the worse, the overhanging of the spectacles with light transmission control lenses mounted thereon ruins the shapely design of rimless spectacles.
Furthermore, recently, a pair of spectacles to improve both far and near vision which enables the wearers to look at a far sight and to carry out chores at hand without changing the glasses has been favorably received by the wearers since a dual focus lens and progressive focus lens with a focus region for far sight and that for near sight integrated therein have been developed. However, in addition to the fact that such lenses are very expensive, because their far and near focus regions are narrow, in either cases where the conventional spectacles of such type is used to look at a far sight and used to do chores at hand, for example, reading, due to narrowness in its effective field of vision, especially in the latter case, it causes strains of the eyes, so that when they do chores at hand for a long time, they could not help wearing a pair of spectacles exclusively used therefor and when they look at a far sight for a long time, driving, for example, they could not help wearing a pair of spectacles exclusively used therefor.
In view of the above-mentioned inconveniences encountered when the wearers want to add other optical functions to the spectacle lenses in use or switch those lenses with other types thereof, the present invention is to provide a new method for efficiently working an auxiliary spectacle lens which is light in weight and is easy to be stably mounted in front of the respective lenses of the spectacles in use.